Leon Trotsky was exiled here for a few years.
In 1951, the railway from Taishet reached Ust-Kut. The town thus became the first and only river port on the Lena served by the railway, and an important railhead through which cargoes could travel to and from the locations along the Lena, such as most of Yakutia. Ust-Kut remained the end of the line until 1974, when construction work started to extend the railway, now known as the Baikal Amur Mainline, east toward the Lake Baikal and beyond. The city became the headquarters of the construction of the western section of the BAM.